Removal of gas and low-boiling fractions from petroleum products



Aug. 18, 1931. w, G. WHITMAN ET AL, 1,819,760

REMOVAL OF GAS AND LOW BOILING FRACTIONS FROM PETROLEUM PRODUCTS I FiledMarch 9, 1927 Patented Aug. 18, 1931 PA-TENT OFFICE UNITED I STATESWALTER G. WHITMA AND CLABKE- C. MILLER, OF WRITING, INDIANA, .ASSIGNOBST STANDARD OIL COMPANY,` 0F- 'WHITING, INDIANA, A COBPOATION, OFINDIANA.

EEMovAL or GAS Ami Low- Bourne rnacv'rIoNsrRoM PETROLEUM rnonucrrsApplication filed March 9, 1927. Serial No. 173,918.

This invention relates to the removal of gases and low boiling fractionsfrom petroeum products and particularly from gasoline andgasoline-containingdistillates from pressure cracking operations.

The invention will be readily understood from the following descriptionof a preferred method of operatingA in conjunction with y theaccompanying drawings in which: Figure 1 is an elevation partly insection ofdan apparatus suitable for this purpose; an v Fig. 2 is afragmentary view illustrating a modification of the apparatus.

Referring to the drawin s, 10 is a receiving drum, adapted to be suppied With distillate by pipe 11 which is provided witha reducing valve12. From the top of drum 10, a pipe 13 leads to suitable collecting orabsorbing ap- 20 paratus (not shown) and pipe 13 is provided withsuitable means (not shovvn) for maintaining the pressure in drum 10 at adesired degree. Fromthe bottomof drum 10 a pipe f 14 leads to a heatexchanger 15, which may' 25 suitably be o f the double tube type. Theoutlet from the heat exchanger 15 feeds into a pipe 16 lwhich leadsinto'a separating chamber or drum 17. A pipe 18 and suitable valves rmay be provided s0 as to enable the heat ex- 30 changer to be by-passedwhen desired. VIn the pipe 16 a suitable reducin valve 19 is provided.From the bottom o theseparatmg drum 17, a pipe 20 leads into a coil 21in the upper part of a fractionating column 22.k

3? A i e 23 and suitable valves may beprovi ed) so as to enable theseparating drum 17 tov be bypassed when desired. The outlet ipe24 fromthe coil 21 passes through the liest exchanger 15 and leads into aninter- 4 mediate part of the column 22. From the top of the separatingdrum 17, a valved pipe 25 leads into an intermediate part of the co umn22. A valvgd pipe4 37 connects with the pipe,

25 and leads to an absorbing apparatus or storage system (not shown).Thecolumn 22 is provided with suitable fractionating devices, which maysuitably be bubble-cap plates provided with bubble-caps and over-v 4flow pipes. From the top of the column a vaw por outlet leads to anabsorption plant .(not shown). In the base of thecolumn 22 suitableheating means may be provided. As shown in Fig. 1 the heating means maybe a perforated pipe 26 which is adapted to inject lsteam into thedistillate'which collects in the base of the' column. From the base ofthe column 22 a pipe 27 leads to a receiver 28 provided with a gaugeglass 29, avalved Water outlet pipe 30 anda distillate outlet ipe 31.The ipe 31 leads into a cooler w ich may vsuita ly be a chamber 32providedwith a coolingcoil 33 and an outlet 34.

As shownl in Fig. 2 the heating means may be a closed steam coil 35 andin this modification the receiver 28 may be omitted, the outy letpipe 27leading directly into the cooling chamber 32.

The operation will be fully understood from the following illustrativeexample.

`Pressure distillate condensed and further cooled with Water, underabout 300 lbs. gauge pressure, is admitted by pipe 11 through reducingvalve 12 into the drum 10 which is maintained at a pressure of about 8.0lbs. gauge. `The gas and vapors separating in drum 10 are passed byApipe 13 to suitable absorption apparatus (not shown) The temperature ofthe oil drops about 10 F. owing to the expansion effected at valve'l12,the temperature of the oil in drum 10'being, for ex'- ample, about F.Oil from drum 10 is passed by pipel 14 to heat exchanger 15, and passingthrough theI outer pipe thereoLis cooled to about 50 The oil then passesthrough reducing valve 19 and its pressure is reduced to substantiallyatmospheric, its tempoint of the column, or, if desired, is removed fromthe system by pipe 37. The liquid oil is passed through the coil21,-thereby maintaining a low temperature in the head of the column,thus providing reflux for the columnV and reducin to the extent desiredthe amount of gasoline constituents carried off by the gases which passout of the column by pipe 36.

The oil issuing from the coil 21 has a temperature of about 39 F. andpassing through the heat exchanger 15, serves to effect the precoolingof the incoming oil as hereinbefore described. The oil emerging from theheat exchanger 15 by pipe 24 has been heated therein to about 50 F. andis fed by said pipe into an intermediate point of the-column 22. Beforebeing thus supplied to the column, the oil may be further heated, ifdesired, by any suitable means, for example, by the khot oil withdrawnfrom the still. The oil thus supplied, together with reflux from the uper part of the column descends through t e column over the bubble-capplates below its point of ent gradually increasing in temperature andeing intimately contacted with gas and vapors derived from the heatedlower end of the colunm. A body of oil is collected and maintained inthe lower portion of the column and is maintained at a temperature suchas about 130 F. sufficiently high to ensure absence of any substantialquantities of ases and wild ends in 'the finished distillate.

his temperature may be maintained by injecting open steam into the bodyof oil as lllustrated in Fig. l or by -passing steam lirough a closedcoil therein as illustrated in The gases and vapors fed into the columnby pipe 25 together With'the gases and vapors liberated in the lowerpart of the column, ascend through the upper part of the column, beingtherein. intimately contacted with the reflux condensed by coil 21, andsubjected to gradually decreasing temperature. treatment gasolineconstitutents are condensed from the ascending gases and contact withthe coil 21 effects a further condensation of such constituents.

Pre-cooler 15 may be by-passed andsupplementary cooling means may beused in the apparatus, if desired. Further, the separating drum 17 maybe omitted or by-passed, if desired, and both gases and liquid may bepassed through the cooling coil 21.

The method exemplified by the foregoing detailed example el'ects theremoval of gases and wild va ors while retaining substantial quantitiesoi) valuable low-boiling gasoline constituents which would be carriedolf by said gases and vapors if the distillate .were

subjected to natural weathering or rerunning.

Although the present invention has been' described in connection withthe details of a specific embodiment thereof, it is not intended thatsuch details shall be regarded as limitationsupon the scope of theinvention, except in so'far as included in the accompanying claims.

We claim: v 1. The method of removing gases and low,- boiling fractionsfrom hydrocarbon distil- 4lates. which consists in reducing the resmreon such distillate thereby liberating gas In this therefrom, expandingthe gas while in the presence of said distillate to reduce thetemperature of the distillate, passing the chilledl .mg the distillatein heat exchange relationship with incoming distillate, passing .saidfirst mentioned distillate into an intermediate part of said column, andapplying heat at a lower part of said column.

3'. The method of removing gases and lowboiling fractions from'hydrocarbon distillates which consists in reducin the pressure on such.distillate thereby li eratmg ga's therefrom, and causin the Gas toexpand while in the presence o said distillate to re.- duce thetemperature of the distillate,pass ing the chilled distillate through a'closed conduit in the upper part of a fractionating column, supplyingvsaid distillate and gasto an intermediate point of said column, andapvplying heat at a lower part of said column.

4. The method of removing gases and low- 'boiling fractions fromhydrocarbon distillate which consists in reducing the pressure on slchdistillate thereby liberating gas therefrom, expanding the gas andreducing the temperature of the distillate, separatin said gas from saiddistillate, passing the c illed distillate through a closed conduit inthe upper part lof`a fractionating column, supplying said distillate toan intermediate point of said column, supplying said separated gasseparately to an intermediate point of said column, and supplying heatat a lower part of said column.

5. The method of removing gases and lowboiling fractions fromhydrocarbon distillate which consists in reducing the pressure of suchdistillate thereby liberatinggas therefrom, expanding the as andreducing the temperature of the distillate, separatingisaid is from saiddistillate, assing the chilled 'stillate through a close conduit in theupper part of a fractionating column, then pass- 1n the distillate inheat exchange relationship with incoming distillate, passing said firstmentioned distillate into anintermediate point of said column, passingthe separated gas into an intermediate point of said column, andapplying heat at a lower part of said column.

6. The method of removing gases and lowlmi - plying distillate underboiling fractions from hydrocarbon distillates under high pressure whichconsists in reducing the pressure thereon to a pressure substantiallyabove atmospheric pressure, rep,

into the column at an intermediate point of` v said column and applyingheat at a lower part of said column.

7. The method of removing gases and lowboiling fractions fromhydrocarbon distillates under high pressure which consists in reducingthe pressure thereon to a pressure substantially above atmosphericpressure, removing the gases and vapors thereby liberated, thenreducing'the pressure on said distillate to substantially atmosphericpressure, thereby liberating gas therefrom while causing the liberatedgas to expand in the presence of said distillate to reduce thetemperature of the distillate, passing the chilled distillate through aclosed conduit in the upper art of a fractionating column, then passingthe distillate in heat exchange relationship with incoming distillate atsuperatmospheric pressure, then introducing the first mentioneddistillate into the column at an intermediate point of said column andapplying heat at a lower part of said column. e

8. An apparatus for removing gases and low-boiling fractions fromhydrocarbon distillates which comprises a conduit for supplyingdistillate under pressure, a reducing valve therein, a ractionatingcolumn, a closed conduit in the upper part of said column and adapted tobe supplied with distillate from the first said conduit, a heatexchanger, a conduit leading from the closed conduit in the upper partof the column into an intermediate ypoint of said column and located inheat exchange relationship with therst said conduit so as to cool thedistillate under said pressure passing therethrough, and means forsupplying heat to the lower part of said column.

9. An apparatus for removing gases and "low-boiling fractions fromhydrocarbon distillates which comprises a conduit for suppressure, areducing valve therein, a separating drum into which said-conduit feeds,a fractionating column, a closed conduit in the upper part of saidcolumn adapted to be supplied with distillate from said drum, means forconveying distilate from the conduit in the column into an intermediatepoint of said column, means for supplying gases from the separatingdruminto an intermediate point of said column, and means for supplying heatto the lower part of said column. v

10. An apparatus for removing gases and low-boiling fractions fromhydrocarbon distillates which comprises an' expansion drum, aconduitleading thereinto, a reducing valve 1n sald conduit, a second expansiondrum, a condult for leading liquid from the first drum into the seconddrum, a reducingvalve in said conduit, a fractionating column, means forsupplying heat to thelower part of said column, a closed conduit in theupper part of sald column, means for supplying liquid oil from thesecond separating drum thereto, means for supplying gases and vaporsseparated 1n the secondexpansion drum to an intermediate point of said4column, a heat exchanger and means for conveying liquid oil .from theclosed conduit in the column to an lntermediate point of the column, thelast said means and the conduit leading from the first expansion drum tothe second being located in heat exchange relationship so as to cool'theincoming oilbefore it passes through the second reducing valve.

11. A method of utilizing pressure distillate from cracking operations,which comprises cooling said distillate by reducing the pressure thereonto liberate gas therefrom and cause sald liberated gas to expand in thepresence of said distillate, passing the cooled distillate in a confinedstream through the upper part of a fractionating column, thenintrpduclng said distillate with its contained gas into an intermediatepoint of said column,

. and supplying heat ata lower part of said column.

WALTER G. 'WHITMAN CLARKE C. MILLER.

